# CalcTracker > CalcTracker is an ultra-fast, offline-first suite of multipurpose calculators for discounts, VAT, margins, percentages, sales tax, property taxes, financial calculations, utilities, and health indexes (BMI/BMR), fully localized in 10 languages. ## Key Features & Philosophy - **Fully Client-Side**: All calculations are performed instantly in the browser. Zero data is sent to external servers or stored remotely, ensuring absolute privacy. - **Offline-First**: Once loaded, all calculators operate 100% offline without requiring any internet connection. - **Dynamic State Sharing**: Calculations can be instantly shared via generated query parameter URLs, which auto-populate fields for other users. - **Multilingual Support**: Fully localized in English, Italian (Italiano), Spanish (Español), French (Français), German (Deutsch), Portuguese (Português), Dutch (Nederlands), Polish (Polski), Turkish (Türkçe), and Romanian (Română). ## System URLs & Navigation Structure Users and crawlers can navigate to specific language roots or direct calculator slugs: - [/en](/en) — English Homepage (Discount Calculator primary) - [/it](/it) — Italian Homepage - [/es](/es) — Spanish Homepage - [/fr](/fr) — French Homepage - [/de](/de) — German Homepage - [/pt](/pt) — Portuguese Homepage - [/nl](/nl) — Dutch Homepage - [/pl](/pl) — Polish Homepage - [/tr](/tr) — Turkish Homepage - [/ro](/ro) — Romanian Homepage To access any calculator, use the path pattern `//`. For example: - [/en/discount-calculator](/en/discount-calculator) - [/it/discount-calculator](/it/discount-calculator) (Calcolatore Sconti) ## Primary Calculators (Slugs & Identity Keys) ### Core Financial & Math Calculators - [Discount Calculator](/en/discount-calculator) — Easily calculate sale price reductions, percentage savings, and saved cash amounts. Supports "Reverse Discount" to reconstruct original price from discounted sum. - [Percentage Calculator](/en/percentage-calculator) — Solve standard proportion equations (e.g. what is X% of Y, what percentage is X of Y, percentage increase/decrease). - [VAT Calculator](/en/vat-calculator) — Compute gross with VAT or perform VAT extraction/peeling (scorporo) using localized european rates. - [Margin Calculator](/en/margin-calculator) — Deduce revenue margins, markup ratios, sales profits, and gross yields based on purchasing costs. - [Reverse Discount Calculator](/en/reverse-discount-calculator) — Specialized reverse pricing tool to deduce the starting retail price before markdown. - [Sales Tax Calculator](/en/sales-tax-calculator) — Swiftly apply and track general sales taxes. - [Price Change Calculator](/en/price-change-calculator) — Measures delta modifications, cost variations, and inflation percentage shifts between historic and current values. - [Inflation Calculator](/en/inflation-calculator) — Trace actual purchasing power depreciation or appreciation across custom currency eras. - [Math Calculator](/en/math-calculator) — Solve advanced math operations, logarithmic expressions, and standard functions. ### Property & Extra Finance - [IMU/TASI Calculator](/en/imu-tasi-calculator) — Estimate Italian property tax obligations (IMU) using cadastral rent rates and local tax indexes. - [Mortgage Calculator](/en/mortgage-calculator) — Graph loan installments, interest schedules, and mortgage principal decays over months or years. - [Pension Calculator](/en/pension-calculator) — Outline retirement horizons, age requirements, and estimated savings returns. - [Future Value Calculator](/en/future-value-calculator) — Evaluate standard compounded investment portfolios or return futures. - [Compound Interest Calculator](/en/compound-interest-calculator) — Forecast compounded investment yields over flexible periodic increments. - [Loan Interest Calculator](/en/loan-interest-calculator) — Calculate personal loan bills with dynamic percentage rates, processing fees, and amortization plans. ### Health, Fitness & Vital Utility Calculators - [BMI Calculator](/en/bmi-calculator) — Check Body Mass Index (BMI) using metric or imperial metrics to determine healthy weight categories. - [GFR Calculator](/en/gfr-calculator) — Calculate estimated Glomerular Filtration Rate (eGFR) using CKD-EPI, MDRD, Cockcroft-Gault, and Bedside Schwartz formulas. - [BMR Calculator](/en/bmr-calculator) — Compute Basal Metabolic Rate using Harris-Benedict formulas to define passive caloric burn rates. - [TDEE Calculator](/en/tdee-calculator) — Calculate Total Daily Energy Expenditure based on physical activity levels of the individual. - [Heart Age Calculator](/en/heart-age-calculator) — Provides indicative cardiovascular age and habits wellness indicators. - [Net Salary Calculator](/en/net-salary-calculator) — Assess net salary taking into account tax brackets, deductions, and regional security costs. - [Car Tax Calculator](/en/car-tax-calculator) — Italian car tax (Bollo) calculator using engine power input (kW / HP) and regional tariffs. - [Pregnancy Calculator](/en/pregnancy-calculator) — Map estimated baby delivery dates (EDD), trimester checkpoints, and fetal age. - [Pet Pregnancy Calculator](/en/pet-pregnancy-calculator) — Gestation counters for canine and feline pregnancies. - [Water Intake Calculator](/en/water-intake-calculator) — Recommends hydration goals based on active hours, physical weight, and environment climate. - [Clothing Size Calculator](/en/clothing-size-calculator) — Map shoe and clothes sizes across international formats (US, UK, EU, IT, JP). ### Administrative & Daily Productivity Tools - [Hours Calculator](/en/hours-calculator) — Calculate elapsed time duration between start and end times or add and subtract hours and minutes. - [Days Between Dates Calculator](/en/days-between-dates-calculator) — Compute clean days, weeks, months, or year calendars between arbitrary historical dates. - [Age Calculator](/en/age-calculator) — Get exact age calculations down to weekdays, upcoming birthday plans, and leap-year details. - [Word Counter Calculator](/en/word-counter-calculator) — Analyze writing layouts, counting paragraphs, letters, average reading duration, and character metrics. - [Currency Converter](/en/currency-converter) — Lightweight online converter of primary regional currencies. ## Schema Markup & Crawler Compliance Every page serves rich structured schemas (`application/ld+json`) matching: 1. `BreadcrumbList`: To provide clean pathing structures for search engine crawlers. 2. `FAQPage` (Answer blocks): Detailed question-and-answer indexes nested on each calculator screen to ensure immediate AI indexing. 3. `HowTo`: Step-by-step guidance for each calculator based on worked examples.